Percussion fuse



ocr. 13, 1936. M, BIRKIGT 2,057,410

PERCUSSION FUSE Filed Maroh'2'7, 1936 i Y i Patented Oct. 13, 1936 UNITED STATES PATENT OFFIQE Application March 27,

1936, Serial No. '71,327

YIn Belgium January 18, 1936 6 Claims.

The present invention relates to percussion fuses for projectiles rotating about their axis along their trajectory and it is more especially, although not exclusively, concerned with fuses of this kind for projectiles of small calibre.

The object of the present invention is to provide a `fuse of thiskind which isbetter adapted to meet the requirements of practice than similar fuses made up to the present time.

The essential feature of the present invention consists in providing balls or the like for locking the striker of the fuse as long as it is necessary, and `in providing, around said balls, a chamber the walls of which are in the shape of a body of revolution, having notches formed therein for accommodating the balls, which can thus move out of locking engagement with the striker, the whole -being arranged in such manner that the balls, which turn with respect to said walls under the effect of the rotary movement of the projectile can penetrate into these notches only when the speed of said balls is little different from that of the wall of said chamber.

Other features of the present invention will result from the following detailed description of a specic embodiment thereof.

A preferred embodiment of the present invention will be hereinafter described, with reference to the accompanying drawing, given merely by Way of example, and in which:

Fig. l is an axial sectional View of a percussion fuse according to the present invention;

Figs. 2, 3 and 4 are views, similar to Fig. 1, `showing the parts in diierent relative characteristic positions thereof;

Fig. 5 is a perspective view of one of the elements of the fuse;

Fig. 6 is a sectional view on the line II-II of Fig. 2;

Fig? is a sectional view on the line III- III of Fig. 3.

The invention will be described in detail with reference to a fuse for a shell intended for a gun the tube of which is provided with riings.

The principle of the invention consists in locking the striker of the fuse by means of balls enclosed inside a cage which prevents them from escaping radially, said balls releasing said striker when they are allowed to move away from said striker to a certain distance therefrom.

According to the invention, said cage is provided with notches into which the balls can penetrate, but only after their speed of revolution "about the axis of the projectile has reached a value approximating the speed of revolution of the cage.

It will be readily understood that, immediately after the shot has been fired and as long as the speed of revolution of the balls about the axis of the projectile is substantially lower than the speed of revolution of the cage, the notches move too quickly past the balls for permitting them to penetrate thereinto.

On the contrary, when the relative movement of the balls and the notches is slowed down, the balls can enter said notches and release the striker of the fuse.

This device is advantageously made in the following manner:

Concerning rst the body of the fuse, it consists of a hollow metallic part I which is prolonged rearwardly, in the usual manner, so as to form a chamber 2 in which are placed the detonator 3 and the priming charge 4. This chamber is closed by a stationary piece 5, in the center of which there is provided an orice 6, through which a striker 'I is slidably guided.

The front part of body I is hollowed out so as to form a chamber 8 communicating, at its front part with an axial bore 9, closed, at the front part, by a small plate I0.

The striker 'I includes, on the one hand, a head II adapted to slide in bore 9, and, on the other hand, an enlarged portion I2, located for instance in the intermediate part of said striker, said enlarged portion forming a stop adapted to cooperate with locking balls I3.

I further provide, in chamber 8, an element capable of preventing a rearward displacement of the balls, said element consisting, for instance, as shown by the drawing, of a cylindrical sleeve I4 carried by piece 5 and the front edge of which is of conical shape, with an apical angle of say 120.

Furthermore, I provide means whereby the balls are held between enlarged portion I2 and sleeve I4 before the shot is red, Whereas, immediately after the shot has been fired, the notches adapted to cooperate with said balls are brought opposite said balls.

These means may be devised as follows:

Chamber 8 is made of a shape such that its lateral wall surrounds, with a slight peripheral clearance space, balls I3 in the locking position thereof, notches I5 being provided in said wall opposite said balls. Between balls I3 and said wall, there is interposed a partition, either adapted to be easily torn (paper, tin sheet) or adapted to be moved out of the way when the shot is red, under the effect of inertia.

Such a partition would suffice to keep the balls in locking position under normal conditions and would leave them free to move away under the effect of the centrifugal force.

However, I deem it preferable to employ the arrangement shown by the drawing.

In this case, there is provided, in chamber 8 behind bore 9, a longitudinal housing I6, for instance atleast partly cylindrical and which may extend rearwardly around sleeve I4. In any case, the enlarged portion I2 of the striker must be located in the front part of said housing I 6 (Figs. 1 to 3).

In this housing I6 there is housed a ring-shaped member I1, preferably cylindrical and of uniform thickness, securely but elastically held in said housing. For instance, as shown by Fig. 5, said ring-shaped member is slit, and it is given a size such that it is necessary to contract it from inserting it into housing IB. The friction thus produced is suflicient for preventing any displacement of said member Il' in housing I5 as long as said member is not urged by an enormous force,rsuch as that which acts on the parts when the shot is fired.

This ring-shaped member I'I is made of such a height and thickness that, on the one hand, in its front position (Fig. 1), which it is given when the parts are assembled, its rear part is located inthe same transverse plane of the balls when the latter are located between sleeve Ill anden- Ylarged part I 2, thus keeping said balls in the locking position, and, on the other hand, in its rear position (Figs. 2 to .4), said member I1 has its frontpart in the same transverse plane as the balls, which it would still keep in the locking position if said front part of member Il were not especially devised.

This front part of member I1 is provided with notches I5 such that, in the rear position of member Il, said notches are in the same transverse plane as balls I3 for the locking position of said balls. These notches are made of such asize that a ball I3 can freely enter into each of them and that, after havingv entered said notches, said balls can move out therefrom toward the front of the front edge of ring I'I, by moving around the edge of enlarged portion I2 of the striker.

Advantageously, the device above described is completed by providing, in housing I6, a peripheral groove I8 devised in such manner that, after passing through the notches, balls I3, instead of coming into contact with a cylindrical wall, meet aconical wall,`of an apical angle of say 60, along which they roll and simultaneously move toward vthe front, under the effect'of the centrifugal force,

so as to nally'reach (Fig. 4) the front portion, of larger diameter, of said groove I 8.

' The operation of a fuse as above described, the various parts-of which are arranged, in the position'ofjrest(corresponding to the locking of the striker) as shown by Fig. 1, takes place as follows: f ,Y l

When the shot isredfring shaped member I'I moves ina rearward direction (Fig. 2) and Vthenotches are Vbrought into the transverse plane ofjthe balls, said balls being, due to the enormous; acceleration imparted to the shell in the gun, strongly applied against the conical upper edge of sleeve I4, and therefore urged toward the axis of the fuse.`

;When the acceleration ceases, that is to say after the shell has left the gun, the balls come into contact with ring-shaped member I1 (Fig. 6) but, while said member rotates with a speed of revolution equal to that of the projectile, said balls turn at a much lower rate, due to their inertia, and therefore they roll inside ring-shaped member il without being able to enter the notches, due to the difference between the speeds of rotation.

However, the speed of revolution of the balls increases owing to their friction against the projecting parts existing between the notches l5 and after a short time, the speed of revolution of Vthe balls approximates that of ring-shaped member I1.

Then (Figs. 3 and 7), all the balls penetrate into corresponding notches and being urged frontwardly due to the slowing down of the movement of the projectile along its trajectory and also to the conical shape of the sleeve I4, they move toward the front beyond 'the'enlarged portion I2 of the striker, after having caused the latter to move slightly frontwardly.

'Ihe striker is then released and when the shell meets with an obstacle, said striker is free to act on the detonator.

It will be readily understood that the time necessary for releasing the striker determines the margin of safety. This time may be varied by acting, among other things, on the mass of the balls, the number of said balls, the Width of the notches, which may be substantially greater than the diameter of the balls and the shape of the solid parts extending between said notches. It is therefore possible to adjust at will the distance from which, after having left the gun, the shell shall be capable of exploding.

Advantageously, the number of balls is equal to the number of notches (for instance four), but the number of said elements might be different.

In a general way, while I have, in the above description, disclosed what I deem to be a practical and eiicient embodiment of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. A fuse for a projectileintended to move along its trajectory with a rotary movement about said trajectory which comprises, in combination, a fuse body, a detonator carried by said body, an axial striker movable in said body for action on said detonator, an annular element rigid angularly wth'said body coaxially surrounding said striker, a plurality of members normally applied against said striker so as to lock it in a position out of contact with said detonator, said members being adapted to run with a rolling movement on the inner Wall of said element, said element being provided with a plurality of recesses adaptedto accommodate said members so `as to permit said members to move radially away from said striker and thus to unlock it, whereby said unlocking action takes place only when, due to frictions, said members roll inside said element at a speed approximating the speed of revolution of said fuse about its axis.

2. A fuse for a projectile intended to move along its trajectory with a rotary movement about said trajectory which comprises, in coml bination, a fuse body, a detonator carried by said body, an axial striker movable in said body for action on said detonator, an annular element, rigid angularly with said body, coaxially surrounding said striker, a plurality of members adapted to operatively engage said striker for llocking it in a position out of contact with said detonator, means for keeping said members in the locking position thereof, adapted to be brought out of action by the acceleration undergone by said projectile when it is fired, said members being adapted to run with a rolling movement on the inner wall of said element, said element being provided with a plurality of recesses adapted to accommodate said members so as to permit said members to move radially away from Vsaid striker and thus to unlock it, whereby said unlocking action takes place only when, due to frictions, said members roll inside said element with a speed of revolution about the axis of the fuse approximating the speed of revolution of said fuse about its axis.

3. A fuse for a projectile intended to move along its trajectory with a rotary movement about said trajectory which comprises, in combination, a fuse body, a detonator carried by said body, an axial striker movable in said body for action on said detonator, an annular element, rigid angularly in said body and movable axially with respect thereto, coaxially surrounding said striker, a plurality of balls between said striker and said element adapted to operatively engage said striker, stop means for preventing rearward movement of said balls, whereby said balls, when engaged with said striker, lock it in a position out of contact with said detonator, said annular element fitting with a considerable amount of friction inside said housing in a normal position such that the solid rear part of said element keeps said balls in operative engagement with said striker, said annular element being provided with notches in its front part adapted to come into the same transverse plane as said balls when said element is displaced by inertia in said housing into its rear position, said notches being adapted to accommodate said balls so as to permit them to move radially away from said striker and thus to unlock it, whereby said unlocking action takes place only when, due to frictions, said balls roll inside said annular element with a speed of revolution about the axis of the fuse approximating the speed of revolution of said fuse itself.

4. A fuse according toclaim 3 in which said stop means for preventing rearward movement of said balls consist of a sleeve rigid with said body and the front edge of which is bevelled so as to form an annular cup-shaped bearing for the balls.

5. A fuse according to claim 3 in which said annular element consists of a sleeve, slit longitudinally, mounted with a force fit inside said body.

6. A fuse according to claim 3 in which said body is provided with a chamber having conically divergent walls extending ahead of said notches, whereby said balls after passing into said notches escape frontwardly along the conical walls of said chamber.

MARC BIRIQGT. 

